STEP BY STEP
STEP 1
Identify when a moon will next be in transit. We have mentioned a number of key events in our calendar on pages 50 & 51 with additional details on page 56. Alternatively, the freeware program
WinJUPOS allows you to work out what events are coming up, giving you enough information to plan your observations.
STEP 3
Set your equipment up. Telescopes need time to acclimatise to the outside temperature. For large instruments this may take several hours. Check collimation. Defocus on a medium-bright star and observe the diffraction pattern. If it’s asymmetric, your collimation needs correcting. It’s best to star-test at the focal length you intend to use.
STEP 5
Process each capture with a registration-stacking application such as
RegiStax or AutoStakkert!. Using AutoStakkert! as an example, it’s possible to drag all of the capture files into the application, define the processing parameters for the first one and then batch process them all. If all goes well, the end result will be a set of relatively clear stills.
STEP 2
Choose an image that clearly shows the planet’s disc, moon and shadow. Too small a scale and the motion of the moon and its shadow will be difficult to show over smaller timescales. A focal length of at least 3m is recommended. A Barlow lens or Powermate are ideal ways of upping your telescope’s effective focal length.
STEP 4
Using a mono, high frame rate camera with an infrared pass filter will give the sharpest results. A sequence capture time of up to 90s for focal lengths up to 4m, and 60s for longer setups is recommended. Repeat captures sequentially for at least as long as it takes to show some movement of the moon and its shadow.
STEP 6
The simplest way to animate the images is to load them in sequence in a layer-based editor such as Photoshop. Align all planet discs to the lowest layer. Open the animation timeline control and create as many panes as there are layers, showing a separate layer for each pane. The option to ‘Save for Web…’ allows you save as an animated GIF.